The present disclosure relates to power amplifier circuits and methods, and in particular, to circuits and methods for reducing supply sensitivity in a power amplifier.
A power amplifier is a type of electronic amplifier used to convert a low-power signal, such as a radio-frequency (RF) signal, into a larger signal of significant power, typically for driving a load such as an antenna of a transmitter.
One common application of power amplifiers is in wireless systems. Wireless systems typically include a transmitter and receiver coupled to an antenna to send and receive RF signals. Generally, a baseband system generates a digital signal that includes encoded information (data), and the digital signal is converted to an analog signal for transmission. The analog signal is processed and typically modulated (up converted) to an RF carrier frequency. After up conversion, the RF signal is coupled to an antenna through a power amplifier. The power amplifier increases the signal power so that the RF signal can communicate with a remote system, such as a base station, for example.
Wireless systems require power amplifiers with appropriate gain for amplifying RF signals for transmission with high efficiency. In some applications, power amplifier efficiency may be improved by changing the power supply voltage, Vdd, provided to the power amplifier as the envelope of the RF signal to be transmitted changes. However, changing the power supply voltage also changes the characteristics and behavior of the circuitry inside the power amplifier. Existing solutions for reducing these deleterious effects while maintaining high efficiency are not optimal for meeting the increasing demands of the electronics industry.